Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The intracellular distribution of nitrogen, DPNH cytochrome c reductase, succinic dehydrogenase, and cytochrome c oxidase has been studied in fractions derived by differential centrifugation from rat and guinea pig spleen homogenates. 2. In the spleens of each species, the nuclear fraction accounted for 40 to 50 per cent of the total nitrogen content of the homogenate, and the mitochondrial, microsome, and supernatant fractions contained about 8, 12, and 30 per cent of the total nitrogen, respectively. 3. Per mg. of nitrogen, DPNH cytochrome c reductase was concentrated in the mitochondria and microsomes of both rat and guinea pig spleens. Seventy per cent of the total DPNH cytochrome c reductase activity was recovered in these two fractions. The reductase activity associated with the nuclear fraction was lowered markedly by isolating nuclei from rat spleens with the sucrose-CaCl(2) layering technique. The lowered activity was accompanied by the recovery of about 90 per cent of the homogenate DNA in the isolated nuclei, indicating that little, if any, of the reductase is present in spleen cell nuclei. 4. Per mg. of nitrogen, succinic dehydrogenase was concentrated about 10-fold in the mitochondria of rat spleen, and 65 per cent of the total activity was recovered in this fraction. 5. Cytochrome c oxidase was concentrated, per mg. of nitrogen, in the mitochondria of both rat and guinea pig spleens. The activity associated with the nuclear fraction was greatly diminished when this fraction was isolated from rat spleens by the sucrose-CaCl(2) layering technique. Only 50 to 70 per cent of the total cytochrome c oxidase activity of the original homogenates was recovered among the four fractions from both rat and guinea pig spleens, while the specific activities of reconstructed homogenates were only 55 to 75 per cent of those of the original whole homogenates. This was in contrast to the results with DPNH cytochrome c reductase and succinic dehydrogenase where the recovery of total enzyme activity approached 100 per cent, and the specific activities of reconstructed homogenates equalled those of the original homogenates. The recovery of cytochrome c oxidase was greatly improved when only the nuclei were separated from rat spleen homogenates. 6. Data were presented comparing the concentrations (ratio of activity per mg. of nitrogen of the fraction to activity per mg. of nitrogen of the homogenate) of DPNH cytochrome c reductase in mitochondria and microsomes derived from different organs of different animals. 7. Data were presented comparing the activities per mg. of nitrogen of DPNH cytochrome c reductase in homogenates from several organs of various animals.
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PMID:Intracellular localization of enzymes in spleen. I. Reduced diphosphopyridine nucleotide cytochrome c reductase, cytochrome c oxidase, and succinic dehydrogenase in the rat and guinea pig. 1343 24

The alkaloids from Chelidonium majus L. which had a significant inhibitory effect in mitochondrial respiration were those which contain a positive charge due to a quaternary nitrogen atom, i.e., chelerythrine, sanguinarine, berberine and coptisine, both with malate+glutamate or with succinate as substrates. When malate+glutamate was used as substrate, chelerythrine and berberine, which contain methoxy groups, were particularly more active, since they had a strong effect even at low concentrations. In submitochondrial particles, berberine and coptisine had a marked inhibitory effect on NADH dehydrogenase activity but practically no effect on succinate dehydrogenase activity, whereas chelerythrine and sanguinarine inhibited more strongly succinate dehydrogenase than NADH dehydrogenase, which is in agreement with the results found for mitochondrial respiration. Protopine and allocryptopine, which did not inhibit mitochondrial respiration, strongly inhibited NADH dehydrogenase in submitochondrial particles, but had no effect on succinate dehydrogenase activity.
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PMID:Inhibition of mouse liver respiration by Chelidonium majus isoquinoline alkaloids. 1461 66

We measured the contribution of mitochondrial nitric oxide synthase (mtNOS) and respiratory chain enzymes to reactive nitrogen species (RNS) production. Diaminofluorescein (DAF) was applied for the assessment of RNS production in isolated mouse brain, heart and liver mitochondria and also in a cultured neuroblastoma cell line by confocal microscopy and flow cytometry. Mitochondria produced RNS, which was inhibited by catalysts of peroxynitrite decomposition but not by nitric oxide (NO) synthase inhibitors. Disrupting the organelles or withdrawing respiratory substrates markedly reduced RNS production. Inhibition of complex I abolished the DAF signal, which was restored by complex II substrates. Inhibition of the respiratory complexes downstream from the ubiquinone/ubiquinol cycle or dissipating the proton gradient had no effect on DAF fluorescence. We conclude that mitochondria from brain, heart and liver are capable of significant RNS production via the respiratory chain rather than through an arginine-dependent mtNOS.
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PMID:Mitochondria produce reactive nitrogen species via an arginine-independent pathway. 1651 1

NADH dehydrogenase subunit 2, encoded by the mtDNA, has been associated with resistance to autoimmune type I diabetes (T1D) in a case control study. Recently, we confirmed a role for the mouse ortholog of the protective allele (mt-Nd2(a)) in resistance to T1D using genetic analysis of outcrosses between T1D-resistant ALR and T1D-susceptible NOD mice. We sought to determine the mechanism of disease protection by elucidating whether mt-Nd2(a) affects basal mitochondrial function or mitochondrial function in the presence of oxidative stress. Two lines of reciprocal conplastic mouse strains were generated: one with ALR nuclear DNA and NOD mtDNA (ALR.mt(NOD)) and the reciprocal with NOD nuclear DNA and ALR mtDNA (NOD.mt(ALR)). Basal mitochondrial respiration, transmembrane potential, and electron transport system enzymatic activities showed no difference among the strains. However, ALR.mt(NOD) mitochondria supported by either complex I or complex II substrates produced significantly more reactive oxygen species when compared with both parental strains, NOD.mt(ALR) or C57BL/6 controls. Nitric oxide inhibited respiration to a similar extent for mitochondria from the five strains due to competitive antagonism with molecular oxygen at complex IV. Superoxide and hydrogen peroxide generated by xanthine oxidase did not significantly decrease complex I function. The protein nitrating agents peroxynitrite or nitrogen dioxide radicals significantly decreased complex I function but with no significant difference among the five strains. In summary, mt-Nd2(a) does not confer elevated resistance to oxidative stress; however, it plays a critical role in the control of the mitochondrial reactive oxygen species production.
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PMID:Nuclear and mitochondrial interaction involving mt-Nd2 leads to increased mitochondrial reactive oxygen species production. 1718 52

The senescence process in wheat flag leaves was investigated over a time course from ear emergence until 50% yellowing of harvested leaf samples using an in-house fabricated cDNA microarray based on a 9K wheat unigene set. The top 1000 ranked differentially expressed probes were subjected to a cluster analysis and, from these, we selected 140 up-regulated genes with informative annotations. There was a considerable overlap between this list of genes and genes previously observed to be associated with senescence in other species, covering several functional categories involved in the degradation of macromolecules and nutrient remobilization, notably of nitrogen via the metabolism of carboxylic and amino acids. The up-regulation of a number of genes in this metabolism was confirmed by real-time polymerase chain reaction experiments. The data suggest a role for cytosolic/peroxisomal routes in the integration of the degradation of carbohydrates, fatty acids and proteins, leading to the remobilization of nitrogen. Illustrative examples of up-regulated genes comprise cytoplasmic aconitate hydratase and peroxisomal citrate synthase. The data support a protective role of the mitochondria towards oxidative cell damage via the up-regulation of the alternative oxidase, and possibly also involving the up-regulated succinate dehydrogenase. A number of up-regulated regulatory genes were also identified, notably NAC-domain and WRKY transcription factors. These factors have previously been identified as being associated with senescence in other species. The data support the notion that a generic senescence programme exists across monocot and dicot plant species. However, notable differences can also be recognized. We thus found transcriptional up-regulation of the biosynthetic pathway for benzoxazinoids, a group of graminaceous-specific secondary metabolites.
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PMID:Transcriptome analysis of senescence in the flag leaf of wheat (Triticum aestivum L.). 1720 68

Two different copper complexes with cytosine molecules are formed in the process of crystal growth from the aqueous solution with traces of copper. One of them is diamagnetic, turning into paramagnetic upon ionizing irradiation (complex I). The other, the subject of the present study, is paramagnetic (complex II) as prepared. For complex II, EPR spectra demonstrate that the copper ion is coordinated with one nitrogen atom and three oxygen atoms. On the basis of the detailed EPR spectroscopic analysis and quantum-chemical calculations (in the DFT approach) the model of the complex has been proposed. Both experimental data and the theoretical results support the model with the copper atom, located between the two cytosine ribbons, ligated to a nitrogen and an oxygen atom from two opposing cytosine molecules and two oxygen atoms from water molecules. For complex II the Raman spectra demonstrated concerted restructuring of the hydrogen bonding in the cytosine crystal matrix upon insertion of copper ions.
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PMID:A new cytosine-copper paramagnetic complex spectroscopic study. 1829 14

The bc(1) respiratory complex III constitutes a key energy-conserving respiratory electron transporter between complex I (type I NADH dehydrogenase) and II (succinate dehydrogenase) and the final nitrogen oxide reductases (Nir, Nor and Nos) in most denitrifying bacteria. However, we show that the expression of complex III from Thermus thermophilus is repressed under denitrification, and that its role as electron transporter is replaced by an unusual nitrate reductase (Nar) that contains a periplasmic cytochrome c (NarC). Several lines of evidence support this conclusion: (i) nitrite and NO are as effective signals as nitrate for the induction of Nar; (ii) narC mutants are defective in anaerobic growth with nitrite, NO and N2O; (iii) such mutants present decreased NADH oxidation coupled to these electron acceptors; and (iv) complementation assays of the mutants reveal that the membrane-distal heme c of NarC was necessary for anaerobic growth with nitrite, whereas the membrane-proximal heme c was not. Finally, we show evidence to support that Nrc, the main NADH oxidative activity in denitrification, interacts with Nar through their respective membrane subunits. Thus, we propose the existence of a Nrc-Nar respiratory super-complex that is required for the development of the whole denitrification pathway in T. thermophilus.
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PMID:A cytochrome c containing nitrate reductase plays a role in electron transport for denitrification in Thermus thermophilus without involvement of the bc respiratory complex. 1876 83

A batch culture of Geobacillus sp. NTU 03 was subjected to a rapid temperature shift for investigating the stress response. Several known heat-shock responses for protein, DNA, and cell membrane recurring were observed on two-dimensional (2D) gels. Heat caused protein and cell membrane disruption greatly affected the electron transport chain. Further, heat caused lower dissolved oxygen (DO) solubility resulting in insufficient oxygen to be electron acceptor, and the NADH could not be reoxidized. Hence, we observed seven dehydrogenase that used NADH as electron donor were downregulated on the 2D gels. In contrast, succinate dehydrogenase that used FADH(2) as electron donor was upregulated. However, this induction may simultaneously increase generation of superoxide; therefore the cellular redox state was imbalanced. We observed that superoxide dismutase (2D gel) and zinc ion ABC transporter (mRNA quantification) were upregulated, whereas ferric ion ABC transporter (2D gel and mRNA quantification) was downregulated. Increase in the reactive oxygen or nitrogen species scavenging activities were also observed. For responding the lower DO solubility, a transient activation of nitrate respiration was observed at transcriptional level. Our results support the view that both heat stress and heat-induced stress should be considered together when investigating the stress responses of thermophiles.
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PMID:Stress responses of thermophilic Geobacillus sp. NTU 03 caused by heat and heat-induced stress. 2086 19

The yeast protein kinases Sat4/Hal4 and Hal5 are required for the plasma membrane stability of the K(+) transporter Trk1 and some amino acid and glucose permeases. The transcriptomic analysis presented here indicates alterations in the general control of the metabolism of both nitrogen and carbon. Accordingly, we observed reduced uptake of methionine and leucine in the hal4 hal5 mutant. This decrease correlates with activation of the Gcn2-Gcn4 pathway, as measured by expression of the lacZ gene under the control of the GCN4 promoter. However, with the exception of methionine biosynthetic genes, few amino acid biosynthetic genes are induced in the hal4 hal5 mutant, whereas several genes involved in amino acid catabolism are repressed. Concerning glucose metabolism, we found that this mutant exhibits derepression of respiratory genes in the presence of glucose, leading to an increased activity of mitochondrial enzymes, as measured by succinate dehydrogenase (SDH) activity. In addition, the reduced glucose consumption in the hal4 hal5 mutant correlates with a more acidic intracellular pH and with low activity of the plasma membrane H(+)-ATPase. As a compensatory mechanism for the low glycolytic rate, the hal4 hal5 mutant overexpresses the HXT4 high-affinity glucose transporter and the hexokinase genes. These results indicate that the hal4 hal5 mutant presents defects in the general control of nitrogen and carbon metabolism, which correlate with reduced transport of amino acids and glucose, respectively. A more acidic intracellular pH may contribute to some defects of this mutant.
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PMID:Hal4 and Hal5 protein kinases are required for general control of carbon and nitrogen uptake and metabolism. 2095 80

The mitochondrial ATP-sensitive potassium channel (mK(ATP)) is important in the protective mechanism of ischemic preconditioning (IPC). The channel is reportedly sensitive to reactive oxygen and nitrogen species, and the aim of this study was to compare such species in parallel, to build a more comprehensive picture of mK(ATP) regulation. mK(ATP) activity was measured by both osmotic swelling and Tl(+) flux assays, in isolated rat heart mitochondria. An isolated adult rat cardiomyocyte model of ischemia-reperfusion (IR) injury was also used to determine the role of mK(ATP) in cardioprotection by nitroxyl. Key findings were as follows: (i) mK(ATP) was activated by O(2)(-) and H(2)O(2) but not other peroxides. (ii) mK(ATP) was inhibited by NADPH. (iii) mK(ATP) was activated by S-nitrosothiols, nitroxyl, and nitrolinoleate. The latter two species also inhibited mitochondrial complex II. (iv) Nitroxyl protected cardiomyocytes against IR injury in an mK(ATP)-dependent manner. Overall, these results suggest that the mK(ATP) channel is activated by specific reactive oxygen and nitrogen species, and inhibited by NADPH. The redox modulation of mK(ATP) may be an underlying mechanism for its regulation in the context of IPC. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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PMID:Redox regulation of the mitochondrial K(ATP) channel in cardioprotection. 2109 66


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